I'm not sure if I posted this here before but one of my favourites, perhaps THE favourite, might be short but for me it says so much it doesn't need length:

'Consciousness is not simply a sensory-perceptual affair, a matter of mental imagery, as the contents of our mind would have us believe. It is deeply enmeshed with the brain mechanisms that automatically promote action readiness' - Jaak Panksepp

Suppose a tree fell down, Pooh, when we were underneath it?"
"Suppose it didn't," said Pooh, after careful thought.
Piglet was comforted by this.
- A.A. Milne.